Geological Society of London. 32D 
2. “On the Geological Age of Central and West Cornwall.” By 
J. H. Collins, Esq., F.G.S. 
The author divided the stratified rocks of this district into four 
groups, as follows :— 
1. Zhe Fowey Beds, mostly soft shales or fissile sandstones, with 
some beds of roofing slate; no limestones or conglomerates. These 
beds cover an area of not less than eighty square miles, and contain 
numerous fragmentary fish-remains and other fossils, many as yet 
undetermined, the whole, however, indicating that the beds are either 
Lower Devonian or Upper Silurian. The strike of the beds is N.W. 
to S.E., and they are estimated to be not less than 10,000 feet thick. 
2. The Ladock Beds, consisting of slaty beds, sandy shales, sand- 
stones, and conglomerates; no limestones and no fossils. They cover 
an area of more than 100 square miles to the west and south of 
St. Austell, strike from east to west, and overlie Lower Silurian rocks 
unconformably. They are estimated at from 1000 to 2000 feet thick. 
3. The Lower Silurians consist largely of slates and shales, with 
some very thick conglomerates (one being at least 2000 feet thick), 
some quartzites, and a few thin beds of black limestone. The 
quartzites and limestones have yielded fossils (chiefly Orthide) which 
are pronounced to be of Bala or Caradoe age by Davidson and others. 
The total thickness of these beds is estimated at 23,000 feet, and the 
fossils are found in the upper beds only. Instead of occupying only 
about 12 square miles, as shown on the Survey Maps, they extend 
over nearly 200 square miles, and reach southward beyond the Helford 
River, and westward to Marazion. The strike of these rocks is from 
north-east to south-west. 
4. The Ponsanooth beds occur beneath the Lower Silurians, and 
unconformable with them (strike north-west to south-east); they are 
often crystalline, aud are estimated at 10,000 feet thick. 
Each of these formations has its own set of intrusive rocks; each 
has been contorted and in part denuded away before the deposition of 
its successor. 
The various granitic bosses have been pushed through this already 
complex. mass of stratified rocks without materially altering their 
strike, which does not in general coincide with the line of junction. 
The chemical effects of the igneous intrusions are generally con- 
siderable, and somewhat proportioned to their relative bulk. 
3. ‘On a Second Precambrian Group in the Malvern Hills.” By 
C. Callaway, Esq., D.Sc., F.G.S. 
These rocks occupy an area of about half a square mile on the 
east of the Herefordshire Beacon; they are compact, flinty ‘‘ horn- 
stones,’ very like some of the rocks at Lilleshall, in Shropshire, which 
belong to the newer Precambrian group of the Wrekin. The strike is 
not distinct, but probably is quite discordant from that of the sub- 
jacent gneissic rocks. As in Shropshire, so here, Hollybush sandstone 
and Dictyonema-shales occur on the flank of the Precambrian mass, and 
each seems to have formed an island in the Lower Silurian seas, which, 
during the formation of the May-Hill group, was depressed. In fact, 
in both regions the chief movements of upheaval, subsidence and 
dislocation appear to have been contemporaneous. Thus they are very 
